A side channel attack is one among powerful techniques used to attack encryption algorithms, and such a side channel attack technique has gradually become a great threat to security products. In particular, a power/electromagnetic side channel analysis attack is an attack method of collecting power consumption or electromagnetic waves generated when an encryption algorithm run, and analyzing the secret information (mainly, key information) of the encryption algorithm by performing statistical analysis on the collected power consumption or electromagnetic waves.
Various preventative techniques have been proposed to prevent such a power/electromagnetic side channel analysis attack, and a masking technique is a representative method of preventing the side channel analysis attack using an algorithm. The masking technique is a method of adding random data to original data desired to be encrypted or performing a logical operation, for example, an exclusive OR (XOR) operation, on the original data, so that it is difficult to extract secret information even though statistical analysis is performed on the collected power wave data or electromagnetic wave data.
However, in a symmetric key encryption algorithm, for example, ARIA or SEED encryption algorithm, applied to use such a masking technique, at least two or more masking S-box tables, which are masking look-up tables used in a symmetric key encryption system, need to be generated and stored, so that there is a problem in that resources required for the masking operation, for example, operation time and memory capacity, are excessively consumed.